Package org.eclipse.mat.hprof

Class SeekableStream

java.lang.Object

java.io.InputStream

org.eclipse.mat.hprof.SeekableStream

All Implemented Interfaces:

Closeable, AutoCloseable

public class SeekableStream
extends InputStream
implements AutoCloseable

Used to wrap an non-seekable stream to make it seekable. Constructed with a supplier of the non-seekable stream (which could be a decompression stream or decryption stream). Multiple instances of this stream are then constructed and each starts at the beginning. Optionally supplied underlying seekable SeekableStream.RandomAccessInputStream stream. This is used if the supplier does not provided a fresh underlying stream each time. A seek is used to move the underlying stream to the correct position when switching between unseekable streams. In this case the supplier of non-seekable streams should wrap the innermost stream from the underlying seekable stream with a SeekableStream.UnclosableInputStream so that the non-seekable streams can be closed (to release resources) without closing the underlying seekable.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	SeekableStream.RandomAccessInputStream	Used to wrap and indicate a underlying stream which has a position and has seek().
static class	SeekableStream.UnclosableInputStream	Wraps an InputStream so that close does not propagate to the underlying stream.

Constructor Summary

Constructors

Constructor	Description
SeekableStream(Supplier<InputStream> genstream, int cachesize)	Creates a seekable stream out of a non-seekable stream.
SeekableStream(Supplier<InputStream> genstream, SeekableByteChannel underlying, int cachesize, long estlen)	Creates a seekable stream out of a non-seekable stream.
SeekableStream(Supplier<InputStream> genstream, SeekableStream.RandomAccessInputStream underlying, int cachesize, long estlen)	Creates a seekable stream out of a non-seekable stream.

Method Summary

Modifier and Type	Method	Description
void	close()	Closes and cleans up the SeekableStream, including the non-seekable streams.
long	position()
int	read()
int	read(byte[] buffer, int offset, int length)
void	seek(long pos)	Move to a position in the seekable stream.
long	skip(long length)
String	toString()

Methods inherited from class java.io.InputStream

available, mark, markSupported, nullInputStream, read, readAllBytes, readNBytes, readNBytes, reset, skipNBytes, transferTo

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Details

SeekableStream

public SeekableStream(Supplier<InputStream> genstream,
 SeekableStream.RandomAccessInputStream underlying,
 int cachesize,
 long estlen)
               throws IOException

Creates a seekable stream out of a non-seekable stream.

Parameters:

genstream - Supplier of a new non-seekable stream for the same resource, underlying. The streams are closed when no longer needed. Wrap the innermost stream with SeekableStream.UnclosableInputStream to avoid closing the underlying stream when one of the non-seekable streams is closed by this class.

underlying - The underlying seekable stream. Avoids having to open a file multiple times if a seek can be used instead.

cachesize - number of seekable streams to use

estlen - estimate of length

Throws:

IOException

SeekableStream

public SeekableStream(Supplier<InputStream> genstream,
 SeekableByteChannel underlying,
 int cachesize,
 long estlen)
               throws IOException

Creates a seekable stream out of a non-seekable stream.

Parameters:

genstream - Supplier of a new non-seekable stream for the same resource. The streams are closed when no longer needed. Wrap the innermost stream with SeekableStream.UnclosableInputStream to avoid closing the underlying stream when one of the non-seekable streams is closed by this class.

underlying - The underlying seekable stream. Avoids having to open a file multiple times if a seek can be used instead.

cachesize - number of seekable streams to use

estlen - estimate of uncompressed length

Throws:

IOException

SeekableStream

public SeekableStream(Supplier<InputStream> genstream,
 int cachesize)
               throws IOException

Creates a seekable stream out of a non-seekable stream.

Parameters:

genstream - Supplier of a new non-seekable stream for the same resource. The streams are closed when no longer needed.

cachesize - number of seekable streams to use

Throws:

IOException

Method Details

seek

public void seek(long pos)
          throws IOException

Move to a position in the seekable stream. Locates the stream closest before the seek point. Skip to the seek point. If no underlying stream is before the seek point, create another and discard an existing stream if required.

Parameters:

pos -

Throws:

IOException

position

public long position()

read

public int read()
         throws IOException

Specified by:

read in class InputStream

Throws:

IOException

read

public int read(byte[] buffer,
 int offset,
 int length)
         throws IOException

Overrides:

read in class InputStream

Throws:

IOException

skip

public long skip(long length)
          throws IOException

Overrides:

skip in class InputStream

Throws:

IOException

close

public void close()
           throws IOException

Closes and cleans up the SeekableStream, including the non-seekable streams. Does not close the underlying stream or channel, this should be done explicitly.

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable

Overrides:

close in class InputStream

Throws:

IOException

toString

public String toString()

Overrides:

toString in class Object